Question on regen …

[ColdCase]

Air

Like in a lightning bolt? Or like a high power radio or radar that will jam everything nearby if not cook pedestrians? Or is there a new physics I'm not aware of.

Perhaps the software simply applies the brakes when you lift the throttle to provide the one pedal feel.

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[LivingTheDream]

Not sure that's the case. When HV battery has a high state of charge recuperation is (logically) limited and the energy lost as heat. This does not mean that the motors don't provide braking and only under emergency braking would the rotors come into play.

I'll cite the following article in support of my take on this...
Porsche Newsroom article on Powerful latest-generation PSM motors

Here's the relevant quote:

Recuperation offers further efficiency benefits. Recuperation at up to 240 kW (Macan: 200 kW), depending on the level of brake pedal actuation as well as the temperature and state of charge of the battery (SoC), among other factors. This corresponds to a deceleration of around 4.3 m/s², which is about 40 per cent of the maximum braking power. This means that up to 98 per cent of the total braking energy can be recovered, under everyday driving conditions. If the desired deceleration is greater than the power that can be absorbed via recuperation, the hydraulic brakes are applied. The fine balancing of the braking force via the blending function is imperceptible to the driver.

If you think about it, what would be the reason to place wear and tear (excess heat) on the hard-to-repair/replace motors when you can have the brakes (which are designed to be serviced with replaceable parts) do that work?

 

[PrudentOcean]

I don’t think recuperation generates any more heat than torque generation (driving) does. The motor simply functions as a generator.

 

[W1NGE]

I'll cite the following article in support of my take on this...
Porsche Newsroom article on Powerful latest-generation PSM motors

Here's the relevant quote:


If you think about it, what would be the reason to place wear and tear (excess heat) on the hard-to-repair/replace motors when you can have the brakes (which are designed to be serviced with replaceable parts) do that work?

Precisely - this refers to hard (emergency) braking ) deceleration and not routine braking.

 

[SuperH]

Late to the party on this topic, being as I'm referring to some of the much earlier comments, but for anyone struggling to find the on/off for recuperation, or many of the other settings Porsche has chosen to hide beneath eleventy-twelve layers of menu - just ask the car. I couldn't find the setting in the menu but 'Hey Porsche, turn on/off auto recuperation' did the job. I actually first called it auto regeneration, not recuperation, and that still worked - the car just corrected me lol

 

[dgkhn]

Late to the party on this topic, being as I'm referring to some of the much earlier comments, but for anyone struggling to find the on/off for recuperation, or many of the other settings Porsche has chosen to hide beneath eleventy-twelve layers of menu - just ask the car. I couldn't find the setting in the menu but 'Hey Porsche, turn on/off auto recuperation' did the job. I actually first called it auto regeneration, not recuperation, and that still worked - the car just corrected me lol

Good call! I had assumed Hey Porsche only controlled media/phone/navigation/climate. Now I wonder what else "she" can manage. Cameras? Windows/sunroof/locking? Cruise control settings? Some experimentation is now in order.

 

[SuperH]

Good call! I had assumed Hey Porsche only controlled media/phone/navigation/climate. Now I wonder what else "she" can manage. Cameras? Windows/sunroof/locking? Cruise control settings? Some experimentation is now in order.

I imagine potentially lots of on/off setting options, but perhaps nothing as grand as the sunroof. Let us all know how you get on

 

[W1NGE]

Good call! I had assumed Hey Porsche only controlled media/phone/navigation/climate. Now I wonder what else "she" can manage. Cameras? Windows/sunroof/locking? Cruise control settings? Some experimentation is now in order.

There's a list of commands on the Taycan forum but don't expect the earth - no cruise, locking, etc - heating (its cold or too hot in here works), audio / music, / volume contact calling etc generally yes.

I periodically use it but when simple things like "Hey Porsche, what time is it?" results in "I'm sorry, I did not recognise that command" I give up on it (repeated attempts will get a response).

9 / 10 it's quicker to make the request yourself.

 

[krissrock]

on the regen topic again...
I think i'm starting to understand how this is working...
for some reaon, most of the time when i take the car out, I'm getting 0 Braking regen on the first part of my trips. YET, i can turn on Recuperation, and that will work as designed all the time.

What i've noticed is that if you're braking at a constant rate with a constant rate of braking recuperation, if you then turn on Recuperation at during that braking, you'll see an INCREASE of braking forse and regen!!
This didn't make sense to me at first as I was braking at a constant force/rate, i would expect to see the same rate of regen i was seeing prior to turning on recuperation, since i was already recuperating with the brakes.. (hope this is making sense - basically keep regen off, then while on the brakes, turn it on and you'll see an increase of braking and regen force)

So i'm thinking:
the Regen function (off throttle regen-coasting) is specifically assigned to rear motor.
Braking regen follows normal braking rules > Front first, then rear is added depending on how much break pressure is applied.
Under normal braking, you're probably ONLY getting regen from the front (if regen is off).
This would explain why under normal braking, i see the regen being given by the front...but if i turn on regen during this time, i see an ADDITIONAL regen rate, despite not adding any braking force.


so in order to get the most watts back into the battery, you have to have regen on, to get regen from both axels.
if you have regen off to coast further, when you do get regen from braking, you are only getting regen from the front, unless you're braking hard.

 

[Yves]

@krissrock while I believe your observations are correct, the conclusion is in my opinion wrong, if you use both motors you will decelerate more or in other words it would be very hard to measure the difference you get back at same deceleration, in fact I think you will have more loss if using both motors as they will both heat up and heat is loss and using 2 inverters instead of one will loose more energy …
Also the kWh/100km spent I see a lower consumption with recupuration regen off, as coasting is definitely more efficient …
But I’ll definitely have a look on how regen behaves in the info graphic to see when both motors kick in … thanks for the observation / explanation

EDIT: what I never had or didn’t notice and was mentioned by krissrock, the regen the first KM’s is not active … maybe of the cold / snow was the reason, toggling the regen recup button does activate it, think Porsche still has some work to do …

 

[krissrock]

@krissrock
Also the kWh/100km spent I see a lower consumption with recupuration regen off, as coasting is definitely more efficient …

Yes, i agree...it's more efficient to have regen off....except when braking!
So what i've started doing is toggling it off when accelerating and coasting...then when i know i'm coming to a stop, i toggle regen back on.

it's a bit much, but doing this is helped me see what's happening with the car.

 

[Yves]

Yes, i agree...it's more efficient to have regen off....except when braking!
So what i've started doing is toggling it off when accelerating and coasting...then when i know i'm coming to a stop, i toggle regen back on.

it's a bit much, but doing this is helped me see what's happening with the car.

I do not agree that regen is more efficient with regen on vs using only the braking pedal … On my car it uses the back motor most of the time even with the regen off, since I started watching the graphic I did not see the front motor doing any regeneration, but I drive in a very anticipated way … (maybe the turbo’s stronger back motor does not need the help of the front motor as much)
What I did observe on a cold start however is that I did not have regen, but toggling the switch brought it up immediately … so that is something we observed both.

 

[krissrock]

I do not agree that regen is more efficient with regen on vs using only the braking pedal …

just for my clarity, you feel that recovering energy via two motors is not better than 1 motor?

 

[Yves]

just for my clarity, you feel that recovering energy via two motors is not better than 1 motor?

Yes, if one motor can provide enough deceleration, you only have loss in one inverter instead of 2 …
I’m sure that if I break hard enough and 2 motors are needed they will do so, as long as you can avoid using the break pads …

 

[krissrock]

Yes, if one motor can provide enough deceleration, you only have loss in one inverter instead of 2 …

what do you mean by loss?

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